Conventionally, in a semiconductor manufacturing process, after a wafer is processed in an upstream process (wafer process), the thickness of a wafer has been reduced (hereinafter, also referred to as thinning) in a downstream process for housing into a package. Thinning has been carried out in a state in which the wafer is temporarily bonded onto a supporting substrate by an adhesive agent. Then, after thinning, the supporting substrate is peeled off from the wafer, and the adhesive agent is removed from the surface of the wafer.
Moreover, conventionally, supporting substrates made of glass or made of silicon have been used. The supporting substrates made of glass or made of silicon are expensive and, therefore, are reused for thinning of a new wafer after used for thinning one wafer.
However, conventionally, since an environment and a process for reusing supporting substrates have to be build, the cost cannot be sufficiently suppressed even if the supporting substrates are reused. Moreover, conventionally, removal of the adhesive agent from a wafer has been carried out by peeling or cleaning using a solvent. However, in peeling, since an adhesive agent residue is generated after peeling, there has been a problem of the deterioration of yield. Moreover, in the cleaning using the solvent, since the usage amount of the solvent is large, there have been a problem of high cost and a problem of long cleaning time.
Therefore, it is desirable to carry out thinning of a semiconductor substrate at low cost while ensuring productivity.